The invention relates to an LED light module for a motor vehicle or for a headlight for a motor vehicle, wherein the light module comprises a lens and an LED light source.
An LED light source of this type can be constructed out of multiple light-emitting diodes (LEDs) that are arranged so as to create “one” common light bundle.
A light module such as that mentioned above is essentially composed of one (or more) LED light source(s), e.g., in the form of a high-power light-emitting diode and a lens, can be used to generate a distribution of light that contains light components over the HD line in the generated light pattern. The lighting function thus implemented (example: high beam, object illumination, . . . ) can only be activated in special driving situations, specifically whenever an object to be illuminated is present in front of the vehicle, or the situation allows the high beam to be turned on.
As a result, a light module of this type is active only very rarely, often only for a few minutes per hour depending on the type (high beam, object illumination, . . . ). A light module of this type can thus not be incorporated into creating the night design for the vehicle or of the vehicle headlight; i.e., the region of the light module that is outwardly visible appears dark at night whenever the light module has not been activated, and this is often perceived to be unattractive.
Due to the design of the light module that is required to implement the lighting function (high maximum illuminance, e.g., approximately 150 lux) and the correspondingly limited possibility of reducing the LED light output, it is also not possible to operate the lighting function in the dimmed state without exceeding the legally specified values for stray light.
The object of this invention is therefore to provide a solution to the above-mentioned problem.
This object is achieved by a light module as mentioned above, whereby a diffusion disk is disposed according to the invention between the LED light source and the lens of the diffusion disk as viewed in the light exit direction, wherein the diffusion disk has at least one aperture for the direct passage of at least one component of the light emitted from the LED light source, and wherein the direct component of the light emitted by the LED light source and exiting through the aperture of the diffusion disk is projected through the lens so as to generate a lighting function in the region in front of the motor vehicle.
The lens is able to be fully illuminated homogeneously due to the diffusion disk's being provided, where the light from the primary light source is able to pass unobstructed through the aperture in the diffusion disk, with the result that the main lighting function is unaffected.
This approach enables the light module to be integrated into the headlamp design even with a non-activated lighting function, whereby the diffusion disk is illuminated and the light module accordingly is visually perceptible and does not appear dark.
In a specific embodiment of the LED light module according to the invention, provision is made whereby the LED light source is provided as the primary light source, where essentially the entire emitted relevant luminous flux of this light source emerges through the aperture in the diffusion disk to generate the lighting function.
The term “relevant” luminous flux is understood to refer to that luminous flux that can enter through the light entrance surface of the lens into this lens; this luminous flux thus comprises those light rays that are emitted by the LED light source within the aperture angle of the lens. A light-emitting diode has a given emission behavior depending on the design, with the result that typically a fraction of the light rays—assuming this is not deflected—is emitted in directions at angles that are greater than the aperture angle of the lens, such that this light does not pass into the lens and is thus in principle usable for the lighting function. Light from the LED light source that is emitted at an angle greater than the aperture angle no longer constitutes “relevant” luminous flux.
In an especially advantageous embodiment of the invention, at least one additional LED light source is provided as a secondary light source that is disposed relative to the aperture of the diffusion disk in such a way that the light emitted by the secondary light source is essentially emitted onto the diffusion disk so that essentially no luminous flux from the secondary light source emerges through the aperture of the diffusion disk.
An LED light source of this type can be constructed from one or more light-emitting diodes (LED) that form a “common” light beam. The secondary light source can then be constructed from one or more of these LED light sources—see also below.
A diffusion disk (diffuse disk) that is illuminated by one or more additional LED light sources is used to generate a homogeneously illuminating surface.
Provision can be made here whereby one axis through the LED light source of the primary light source and the aperture of the diffusion disk form the optical axis, and whereby the at least one LED light source of the secondary light source lies outside the optical axis.
This approach in simple fashion prevents the light from the secondary light source from exiting through the aperture of the diffusion disk and thereby causing unwanted interfering radiation.
In order to achieve the optimum, most-homogeneous-possible full illumination of the diffusion disk, or the most homogeneous appearance of the diffusion disk and thus of the light module, provision can be made whereby the at least one LED light source of the secondary light source is displaced to the rear relative to the primary light source and opposite to the exit direction of the light.
A more homogeneous illumination of the diffusion disk is achieved as the distance of the LED light source(s) from the secondary light source increases.
In another embodiment of the invention, provision is made whereby the secondary light source comprises two or more LED light sources for the purpose of obtaining a homogenous full illumination of the diffusion disk.
Another advantageous aspect is that the LED light source of the primary light source and the at least one LED light source of the secondary light source are controllable separately, thereby allowing the primary light source and the secondary light source to be turned on and off independently of each other.
It is furthermore advantageous—when the light module is installed in a vehicle headlight—if the secondary light source of the light module has n LED light sources in the vertical direction below a horizontal plane, which runs, for example, through the LED light source of the primary light source, and has m LED light sources above the horizontal plane, where m<n.
Since the lens of the light module is generally observed from viewing angles above this horizontal plane, it is advantageous for the number of LEDs to be increased in the lower region since this region is projected into the angular region above the horizontal, and as a result a visually more attractive illumination of the lens is able to be achieved.
Just as it is true that the optical axis of the lens does not necessarily have to run through the LED, or through its geometric center in the case of multiple LEDs, the horizontal plane also does not necessarily have to run through the primary LED light source, but instead can be defined by the lens that is displaced vertically, as the result of which the position of the projection (viewing angle) also changes.
In principle, the optimum approach would be a larger number of LED light sources for the secondary light source—however, this would be limited by cost and by the available installation space for the headlight. In a simple, cost-effective variant of the invention by which attractive results can be achieved in fully illuminating the lens/diffusion disk, m=0.
It is furthermore more advantageous in terms of the most uniform possible illumination, if the LED light source(s) above or below the horizontal plane is/are in each case disposed symmetrically in the horizontal direction relative to a vertical plane through the optical axis.
Provision can also be made in this regard whereby additional LED light sources of the secondary light source are disposed laterally adjacent to the LED light source of the primary light source.
In order to be able to optimally utilize the luminous flux from the LED light source of the primary light source, provision is furthermore made whereby the dimensions of the aperture in the diffusion disk—such as, for example, diameter, lateral dimensions, etc., and/or the arrangement of the LED light source of the primary light source relative to the aperture of the diffusion disk, and/or the distance of the LED light source of the primary light source from the diffusion disk—are selected in such a way that coming from the LED light source forming the primary light source all of the emitted light rays that lie within an aperture angle of the lens can pass through the aperture.
The size of the aperture in the diffusion disk is dependent on the distance of the disk from the LED light source of the primary light source and can be derived from the aperture angle of the lens. Since the aperture of the diffusion disk is projected directly through the lens, it is advantageous to implement this aperture to be as small as possible. In addition, the shape of the aperture is preferably matched to the shape of the trimmed lens.
The diffusion disk is positioned as close as possible to the LED light source of the primary light source so as to minimize the size of the aperture.
In terms of the shape of the trimmed lens, it is especially important what shape the light entrance surface of the lens has. The lens here has a flat or curved surface with, for example, a circular (square, rectangular) shape, or any shape based on the application, the shape here being identified as the “shape of the trimmed lens.” Proportionally, the shape of the aperture here is preferably identical to the trimmed lens.
The shape of the diffusion disk is preferably implemented so that it is visible through the projection lens, as seen from outside, from all viewing angles, thereby allowing an effectively homogeneous appearance to be created for the lens.
It is furthermore advantageous if the dimensions of the aperture in the diffusion disk—such as, for example, diameter, lateral dimensions, etc., and/or the arrangement of the at least one LED light source of the secondary light source relative to the aperture of the diffusion disk, and/or the distance of the at least one LED light source of the secondary light source from the diffusion disk—are selected such that light rays are emitted by the at least one LED light source forming the secondary light source only into regions of the diffusion disk that have no aperture.
In this way, no passage of secondary light through the aperture of the diffusion disk can occur, which occurrence would cause unwanted effects.
It is in particular advantageous if the dimensions of the aperture in the diffusion disk—such as, for example, diameter, lateral dimensions, etc., and/or the arrangement of the at least one LED light source of the secondary light source relative to the aperture of the diffusion disk, and/or the distance of the at least one LED light source of the secondary light source from the diffusion disk—are selected such that light rays are emitted by the at least one LED light source forming the secondary light source up to the edge of the aperture of the diffusion disk.
The uniform illumination of the diffusion disk is essentially defined by 3 parameters: distance from the secondary LED light source(s) from the diffusion disk, number of light sources, and arrangement of the light source about the optical axis of the lens, preferably on one or more planes behind the disk, so as to achieve the necessary distance of the secondary LED light sources from the diffusion disk.
The general rule is that the homogeneity of the lens is directly proportional to the number of secondary LED light sources and the distance of the secondary LED light sources from the diffusion disk, a uniform distribution of the secondary LED light source being advantageous.
The installation space available for the light module has a limiting effect on these parameters. On this basis, certain optimized variants are found.
Provision can furthermore be made whereby the edge of the aperture of the diffusion disk tapers down in the direction of the primary light source, e.g., is trapezoidal so as to be optimally matched to the optical path of the marginal rays from the primary light source (marginal rays are those light rays that strike the lens below the aperture angle of the lens).
In terms of the LED light source of the primary light source, this can, for example, be an infrared light source.